The need for landscaping to conserve water received new impetus following the drought of 1977 throughout the western states, and the recognition that nearly 50 percent of the water consumed by the average household is used for turfgrass and landscape plantings. Unfortunately, many homeowners have cut back of turfgrass areas by substituting vast "seas of gravel and plastic" as their answer to water conservation. This practice is not only self-defeating as far as water conservation is concerned, but also produces damaging effects to trees and shrubs. It is not xeriscaping. This fact sheet explains what xeriscaping is and how you can build the beauty and water savings of a xeriscape into your own garden.
Planning - An Important First Step
Whether you plan to redesign an old landscape or start fresh with a new one, a plan is a must. The plan does not have to be elaborate but should take into consideration the exposures on the site. As a general rule, south and west exposures result in the greatest water losses, especially areas near buildings or paved surfaces. You can save water in these locations simply by changing to plants that adapt to reduced water use. However, don’t be too quick to rip out the sod in these areas just to substitute plastic and gravel. Extensive use of rock in south and west exposure areas can cause temperature increases near the house and result in wasteful water run-off.
Slope of Property
Slope or grade is another consideration. Steep slopes, especially those on south and west exposures, waster water through runoff and rapid water evaporation. A drought resistant ground cover can slow down water loss and shade the soil. Strategically placed trees also can shade a severe exposure creating a cooler soil with less evaporation. Terracing slopes helps save water by slowing runoff and permits more water to soak in.
Reduce Irrigated Turf
Avoid narrow strips of turf, hard to maintain corners and isolated island of grass that need special attention. Not only is maintenance more costly, but watering becomes difficult, often wasteful.
Bluegrass turf can be reduced to areas near the house and in places of higher use. In outlying areas, use more drought-resistant grasses or even meadow mixes containing wildflowers, particularly if your property is large.
Soil Preparation
Proper soil preparation is the key to successful water conservation. If the soil is very sandy, water will be lost along with valuable nutrients, due to leaching below the root zone. If your soil is a heavy, clay texture most common in this area, you will lose water through runoff.
A good soil, one that both supports healthy plant life and also conserves moisture, has a balance of rather coarse soil clusters (aggregates), sand and pore spaces. The "ideal" soil will have as much as 50 percent by volume pore space, with the soil itself consisting of a good balance of sand, silt and clay.
A major problem with "heavy" soils is that clay tends to dominate the soil complex. Clay is composed of microscopic crystals arranged in flat plates. When a soil has a high amount of these crystals they act much like a glue, cementing the particles of sand and silt together and resulting in a compact almost airless soil. Such soils usually repel surface water, resulting in runoff. What water does get into these soils is held so tightly by the clay itself that plants cannot use it. Plants in a clay soil, even though it is moist, often wilt from lack of moisture. Plant roots also need air to thrive. In clay soils air spaces are small and may be filled with water, thus plant roots often suffer from oxygen starvation. In very sandy soils, the opposite is true. Sandy soils have very large pore spaces, but because the particles also are large there is little surface area to hold the water, thus a sandy soil tends to lose water rapidly.
A good soil is not made in just one year. Add organic matter to garden areas annually. In areas to be sodded or seeded, add organic amendments as a onetime only procedure. Take advantage of this one time before seeding or sodding by doing a thorough, complete job. This encourages deep roots that tap the water stored in the soil and reduces the need for wasteful, frequent water application.
Xerigation - Saving Water With Proper Irrigation
Proper irrigation practices can lead to a 30 percent to 80 percent water savings around the home grounds. If a sprinkler system is already installed, check it out for overall coverage. If areas are not properly covered or water is falling on hard surfaces, such as driveways and patios, readjust the system. This may mean to replace heads, add more heads, or change the head to do a more efficient job.
With the system on. Observe places that are receiving water where it is not needed. Overlaps onto paved areas or into shrub borders will result in considerable water waste. Overwatering trees and shrubs may lead to other problems. Turf areas should be zoned and irrigated differently than shrub borders and flower beds. North and east exposures need less frequent watering than south and west exposures. Apply water to slopes more slowly than to flat surfaces. Examine these closely in your own yard and correct inefficiencies in irrigation system design.
If you do not have a sprinkler system and are just beginning to install a landscape, you have the advantage of avoiding the pitfalls of poorly designed and installed systems. Have a professional irrigation company do the job correctly. Make sure the system is designed to fit the landscape and the water needs of the plants, and zoned to reduce unnecessary applications of water. Coordinate the landscape design itself, selection of plants and the irrigation system to result in a sensible water-saving scheme. Consider a drip system for outlying shrub borders, raised planters, around trees and shrubs and in narrow strips where conventional above-ground systems would result in water waste.
If hoses are used instead of an underground system, you can observe the same things indicated earlier for sprinkler installations. Instead of watering the entire lawn each time, spot water based upon visible signs of need such as turf areas that begin to turn a gray-green color.
Avoid frequent, shallow sprinklings that lead to shallow root development. Soils that are compact and result in quick puddling and water runoff need aeration with machines that pull soil plugs. Trees and shrubs separate from the lawn are best watered with deep root watering devices.
Xerimulch the Landscape
Properly selected and applied mulches in flower and shrub beds reduce water use by decreasing soil temperatures and amount of soil exposed to wind. Mulches also discourage weeds and can ultimately improve soil conditions.
Mulches are of two basic types: organic and inorganic. Organic mulches include stray, partially decomposed compost, wood chips, bark and even ground corncobs, or newspapers. Inorganic mulches are such things as plastic film, gravel and woven fabrics. Sometimes a combination of both organic and inorganic is used.
If soil improvement is a priority, use organic mulches. Wood chips and compost are most appropriate. As these materials bread down, they become an organic amendment to the soil. Earthworms and other soil organisms will do much to help "incorporate" the organic component into the soil. The organic method of mulching is preferred because most soils in this area are low in organic content and need organic amendments to improve aeration and water-holding capacity.
Inorganic mulches, such as plastic film, effectively exclude weeds for a time, but they also tend to exclude water and air essential to growth of plant roots. The newer woven fabrics and fiber mats now available in many hardware and garden centers are preferred over polyethylene films. Fabrics and mats exclude weeds yet allow water and air exchange. Used in combination with decorative rock or bark chunks, they often outlast the less expensive, but short-lived polyethylene films.